编写以太坊代币合约

pragma solidity ^0.8.4;

// ERC20标准接口 interface IERC20 { function totalSupply() external view returns (uint256); function balanceOf(address account) external view returns (uint256); function transfer(address recipient, uint256 amount) external returns (bool); function allowance(address owner, address spender) external view returns (uint256); function approve(address spender, uint256 amount) external returns (bool); function transferFrom(address sender, address recipient, uint256 amount) external returns (bool); event Transfer(address indexed from, address indexed to, uint256 value); event Approval(address indexed owner, address indexed spender, uint256 value); }

// ERC20标准实现 contract MyToken is IERC20 { string public name; string public symbol; uint8 public decimals; uint256 private _totalSupply; mapping(address => uint256) private _balances; mapping(address => mapping (address => uint256)) private _allowances;

constructor(string memory _name, string memory _symbol, uint8 _decimals, uint256 _initialSupply) {
    name = _name;
    symbol = _symbol;
    decimals = _decimals;
    _totalSupply = _initialSupply * 10 ** uint256(decimals);
    _balances[msg.sender] = _totalSupply;
    emit Transfer(address(0), msg.sender, _totalSupply);
}

function totalSupply() public view override returns (uint256) {
    return _totalSupply;
}

function balanceOf(address account) public view override returns (uint256) {
    return _balances[account];
}

function transfer(address recipient, uint256 amount) public override returns (bool) {
    require(_balances[msg.sender] >= amount, "Insufficient balance");
    _balances[msg.sender] -= amount;
    _balances[recipient] += amount;
    emit Transfer(msg.sender, recipient, amount);
    return true;
}

function allowance(address owner, address spender) public view override returns (uint256) {
    return _allowances[owner][spender];
}

function approve(address spender, uint256 amount) public override returns (bool) {
    _allowances[msg.sender][spender] = amount;
    emit Approval(msg.sender, spender, amount);
    return true;
}

function transferFrom(address sender, address recipient, uint256 amount) public override returns (bool) {
    require(_balances[sender] >= amount, "Insufficient balance");
    require(_allowances[sender][msg.sender] >= amount, "Insufficient allowance");
    _balances[sender] -= amount;
    _balances[recipient] += amount;
    _allowances[sender][msg.sender] -= amount;
    emit Transfer(sender, recipient, amount);
    return true;
}

}